To obliterate intravitreal neovascularization, we will coagulate intravitreal neovascularization with radiofrequency and argon laser and compare the results of both methods. To investigate the technique of vitrectomy we will compare the results of vitrectomy performed in fresh and old vitreous hemorrhages. Finally, we will evaluate the effect of vitrectomy in reattachment of tractional detachments of the retina. This research will be done with four systems which we have designed and developed during our earlier research in this area: 1. A radiofrequency infusion probe for intravitreal coagulation. 2. A vitrectomy instrument (vitrophage) for cutting and removal of the deformed vitreous. 3. A micromanipulator arc system for fine manipulation of the instruments inside the eye. 4. A slit illumination system for visualization of the instruments inside the eye.